WA screwdriver murder accused made threats

A recreational fisherman accused of murdering an Irish father-of-two by stabbing him in the head with a screwdriver during a fight beside Perth's Swan River admits he threatened violence after confronting the 32-year-old over a "racist" comment.

Andrew Doan, 35, had been fishing with his friend Tien Vu Huynh in East Fremantle in the early hours of December 23, 2017 when Charles John McCarthy, his wife Nicole and friend Jason Mikel Curran walked by.

Testifying at his Supreme Court of WA trial on Wednesday, Doan said that when the men saw him and Mr Huynh emerging from the water, they asked "have you caught much?".

He mumbled "not much" in reply and they shot back "bit of s***" luck", according to Doan.

Their next comment - along the lines of "Fisheries are going to come and get you" - upset him and Mr Huynh, who are both Asian and interpreted it racist.

The trio walked off but Doan pursued them and a profane, verbal argument erupted.

Doan said his anger soon gave way to feeling vulnerable and outnumbered when Mr McCarthy began "puffing up" and walked back towards him, "really staunch" with his fists clenched.

"It looked like he was coming into a demonic rage," Doan said.

He said he panicked, reached into his hoodie pocket, pulled out a screwdriver he'd been carrying for crabbing and held it above his head, saying "get back or I'll stab you".

Doan claims that as he retreated to his car, he had a scuffle with Mr Curran and Mr McCarthy kicked a wheelie bin at him, which just missed.

He claimed Mr McCarthy then charged and moved to punch him - ignoring his wife's frantic pleas to stop - and impaled himself on the screwdriver, which Doan was still holding.

Doan insisted he had closed his eyes, thrown his arms up to protect his face and forgot the tool was in his hand.

When he opened his eyes, Mr McCarthy was on the ground, Doan said.

He remained at the scene until emergency services arrived, telling police "it was me" and claiming self-defence.